Francis cradles a baby Jesus statue at start of his first papal Christmas Eve Mass at Vatican

Pope Francis holds a statue of baby Jesus as he celebrates the Christmas Eve Mass in St. Peter's Basilica at the Vatican, Tuesday, Dec. 24, 2013. (AP Photo/Gregorio Borgia) (The Associated Press)

Pope Francis kisses a statue of baby Jesus as he celebrates the Christmas Eve Mass in St. Peter's Basilica at the Vatican, Tuesday, Dec. 24, 2013. (AP Photo/Gregorio Borgia) (The Associated Press)

Pope Francis holds a statue of baby Jesus as he celebrates the Christmas Eve Mass in St. Peter's Basilica at the Vatican, Tuesday, Dec. 24, 2013. (AP Photo/Gregorio Borgia) (The Associated Press)

Pope Francis has begun celebrating his first Christmas Eve Mass as pontiff by placing a baby Jesus statue in a replica of a manger in St. Peter's Basilica.

Francis, who turned 77 a week ago, walked briskly up the main aisle of the basilica, which was packed with faithful and tourists at the start of Mass, which began Tuesday 2 ½ hours before midnight. Keeping with the theme of humility he has set for his new papacy, Francis carried the statue instead of an aide, and kissed a knee of the figure of the newly born Jesus.

The ceremony is the pope's only public Mass for Christmas. On Wednesday, Christmas Day, Francis will deliver his Christmas message, meant for the world, from the basilica's central balcony overlooking St. Peter's Square.